1. Field of the Invention
The present invention relates generally to in-pipe leak inspection, and particularly to a pair of leak detecting submarines that are secured together by a communication and power tether.
2. Description of the Related Art
The problem of water leakage from water pipelines causes clean water loss, energy loss and a major increase in water contamination with hazardous chemicals and metals. Water leakage can reach 50% of the water transported across the water distribution network. It is reported that 30% of the water transported across the Kingdom of Saudi Arabia (KSA) is lost through leakage. These losses are very high and do amount to millions of dollars. Furthermore, the problem of leakage implies penetration of hazardous contaminants into the water distribution system. It has been reported by a group of medical doctors from the department of Oncology, King Faisal Specialist Hospital, Riyadh, Saudi Arabia; that water contamination causing esophageal cancer at Qassim region (KSA) constitutes a major health problem. Furthermore water leaks cause major infrastructure problems by undermining ground stability and, in the process damaging roads and buildings.
A great deal of research work and technology developments have been accomplished in the last two decades to detect water leaks in water distribution networks. Leak detection devices include acoustic leak detection, leak noise correlators, surface listening devices, ground penetrating radar detection methods, and chemical tracing methods as well as X-Ray and infrared radiation methods. In a recent study, the use of leak noise correlators proved unreliable and costly in addition to being time consuming. The use of electronic sound detectors proved more reliable and cost effective. The detectors were placed manually as close as possible to the pipelines.
Recently, a free-swimming leak detection system has been developed to overcome many shortcomings of the acoustic leak detection devices and systems available in the market. The free-swimming leak detector follows the flow of the water and takes advantage of being inside the pipe to clearly detect leaks. The information is stored inside a microprocessor and then downloaded once the detector is extracted from the pipeline. However the motion of this free-swimming leak detection system cannot be controlled by the user and is generally limited by both the shape and dimensions of the pipe, and also by the current flowing through the pipe. Due to the wide variation within pipelines and fluid currents therein, maneuverability and control is desirable in such a free-swimming leak detector.
Further, conventional pipe inspection units, such as pipe inspection gages (PIGs) or present free-swimming robots, require a significant flow velocity within the pipe for propulsion. Thus, in stagnant fluid, or when movement against a current is required, such systems become useless.
Thus, a dual submarine leak detection system solving the aforementioned problems is desired.